CHICAGO, May 8 (UPI) -- Who hasn't engaged in a good round of retail therapy? New top? New shoes? That slinky dress with no place to wear it?

Been there. Done that.

And now researchers at Cornell University and the London Business School say that's perfectly normal behavior -- especially after one suffers an insult. Not only that, a bruised ego is more likely to buy something expensive on plastic rather than pay cash -- despite the associated interest rate costs.

The results of the study could explain how the U.S. economy got into the state it was in and collapsed.

Niro Sivanathan of the London Business School and Nathan Pettit of Cornell University gave two groups of people an ambitious computer test and told members of one group their "spatial reasoning and logic ability was in the 12th percentile" -- science-speak for "you're not very bright" -- and members of the other group their intelligence was in the 88th percentile -- smart enough -- in a study published in the current issue of Social Psychological and Personality Science.

Members of both groups were then asked how they would pay for something they were considering buying.

The researchers found those whose intelligence was questioned were more likely to pay for the purchase on credit.

In a second study, 150 college students were told to consider buying a pair of jeans -- half of them expensive designer jeans. They were given the same computer test and broken into the same types of groups as the previous subjects.

Those who were told to consider expensive jeans and told they weren't very bright were willing to pay nearly 30 percent more for jeans and 60 percent more likely to pay for the extravagance with plastic. Those who had been told before the computer tests to just consider everyday jeans, not the expensive ones, did not increase how much they were willing to pay for jeans -- whether their egos had been bruised or not. When told plastic was not an option, neither group went for luxury items.

"Luxury items are especially effective at reassuring us of our value," the researchers concluded in a release.

"People are likely to resort to credit after threat to consume luxury goods, despite the interest and fees associated with consumer credit."

Seeking luxury after threat, the researchers said, is a normal response.

The researchers say this might explain in part the mortgage bubble that wrecked the economy.

The researchers concluded using credit enabled those who were feeling bad about themselves to ease the pain without inflicting the pain of parting with cash.

"Our results suggest a potential psychological alternative to the economic explanation for the credit crisis that claimed the financial health of many consumers in 2008," the researchers wrote.

"From an economic perspective, the recent rise in credit card debt among the income constrained might be explained, in part, by the fact that their limited financial means forced them to rely on credit for more expensive conspicuous purchases, goods used to speciously signal their status to others. In contrast, although individuals who are low in socioeconomic status often have limited financial means, it is well established that those with low socioeconomic status also tend to suffer lower self-esteem.

"Therefore, in the same way that lower self-worth, a condition common among the income constrained, is shown to drive compensatory spending on expensive high-status goods, this psychological state may be one factor leading consumers to make such purchases with credit. Together, the desire to affirm the self by consuming high-status goods, the preference to do so with credit, and the increased availability of credit among the income constrained may have come together to create optimal conditions for those who could least afford superfluous expenditure to spend more."

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